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942
FXUS66 KMFR 122334
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
434 PM PDT Sat Jul 12 2025

.Updated AVIATION Discussion...

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.AVIATION...
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13/00Z TAFs...VFR prevails across the area this
afternoon. The marine layer remains just offshore north of Cape
Blanco, but this will push inland this evening, bringing the return
of LIFR conditions to the coast north of Cape Blanco that will
persist into Sunday morning. Gusty winds along the coast and in the
Umpqua Basin will ease after sunset. Despite some cumulus buildups
across the higher terrain east of the Cascades and across northern
California, VFR conditions will prevail for inland locations through
the TAF period. /BR-y
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.PREV DISCUSSION... 
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/Issued 251 PM PDT Sat Jul 12 2025/

SYNOPSIS...

Our first notable heatwave will arrive mid July with temperatures
in the mid to upper 100`s and lows in the upper 60`s today and
through Monday. High heat risk will cover valleys west of the
Cascades through this time frame. Beyond that, confidence is lower
if the high heat risk will hang on into early next week.

DISCUSSION...

There is some cumulus buildup on satellite this afternoon over the
higher terrain in the forecast area, especially east of the
Cascades. There is also a weak shortwave just off the California
coastline this afternoon. One can see it on water vapor imagery,
although it is a little harder to pick up. In any case, this wave
will bring a very low chance of thunderstorms in central Siskiyou
County and southern portions of Lake and Klamath Counties on
Sunday.

The SPC HREF lightning probability algorithm is not
picking up on any probabilities above 10%, although it is picking
up on some echos in the model reflectivity for the FV3 and NSSL
models. BUFKIT forecast soundings do show a deep inverted V past
600 mb and 100-200 j/kg of CAPE. When considering all of the data,
there is a low chance of dry thunderstorms over our forecast area
Sunday afternoon east of the Cascades. It`s worth noting any
activity we do see should be well short of what we saw last
Monday as the dynamics are weaker and moisture a little more
marginal.

Aside from thunderstorms, it will be a warm on Sunday with highs
pushing into the mid 100`s west of the Cascades. We`re currently
forecasting 106 here in Medford with a 95th percentile high
forecast of 108. So not much room to get warmer here on Sunday.
Lows will upper 60`s across the board with so chance of 70`s. East
of the Cascades, some sites will into the lower 50`s overnight in
northern Lake and Klamath Counties, so little to no heat risk
there.

These warmer temperatures will continue through Monday, although
things become more interesting by Monday night or early Tuesday
as an upper level low drops down from British Columbia and heads
towards Idaho. A thermal trough will become fairly prominent and
another round of 100 degree temperatures west of the Cascades
should persist into Wednesday.

Nothing really stands out beyond Wednesday except for
temperatures trending cooler towards the end of the week as the
upper air pattern is disorganized with troughing likely in British
Columbia.

-Smith

MARINE...Updated 200 PM PDT Saturday, July 12, 2025...A thermal
trough will strengthen over the waters this afternoon and persist
into Monday. This pattern will bring gusty north winds and steep
wind-driven seas to the waters along with areas of gales and very
steep seas south of Cape Blanco, especially Monday afternoon and
evening. The strongest winds will occur south of Port Orford.
-Smith

FIRE WEATHER...Updated 200 PM PDT Saturday, July 12, 2025...
A stable upper weather pattern will bring continuing warm and dry
weather to the area. An Extreme Heat warning is in place for
Jackson, Josephine, eastern Curry, and western Siskiyou counties. A
Heat Advisory is in place for other inland areas. These products are
in place through Monday night. Additional heat products may
eventually cover Tuesday and Wednesday, as daytime highs remain 5 to
10 degrees above normal through those days. Seasonal winds with
afternoon breezes are expected. Overnight easterly flow is possible
over area ridges, which may bring locally moderate to poor RH
recoveries. Daytime highs may fall below hazard thresholds on
Thursday, although warm and dry conditions are forecast to continue.

Upper level instability moves over the area in the afternoon and
evening of both Sunday and Monday. While cumulus development is
expected, thunderstorm chances remain slight and with isolated
coverage at most. On Sunday, the highest chances (15%) are in
southern Klamath County, with lower chances (5-10%) into Siskiyou
and Lake counties. On Monday, those lower chances (5-10%) are
limited to Siskiyou and Modoc counties. If thunderstorms do develop,
lightning strikes and locally gusty and erratic winds will be
possible.

Some guidance sources are showing a thermal trough developing
towards the middle or end of next week. Under this pattern,
easterly breezes may increase in strength and RHs may further
decrease over our Oregon Cascades. There is slight confidence at
best in this outcome, but the possibility is worth mentioning.
-TAD
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&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Extreme Heat Warning until 8 PM PDT Monday for ORZ024-026.

     Heat Advisory until 8 PM PDT Monday for ORZ023-025-029>031.

CA...Extreme Heat Warning until 8 PM PDT Monday for CAZ080-081.

     Heat Advisory until 8 PM PDT Monday for CAZ082>085.

PACIFIC COASTAL WATERS...Gale Warning until 11 PM PDT Monday for
     PZZ356-376.

     Small Craft Advisory until 11 PM PDT Monday for PZZ350-370.

&&

$$